test(api): Activities — fill gaps + lifecycle test

apps/api/src/routes/activities.ts

@@ -16,6 +16,7 @@ function toActivity(row: ActivityRow): Activity {
     name: row.name,
     insole_types: row.insoleTypes as Activity['insole_types'],
     created_at: new Date(row.createdAt).toISOString(),
+    /* c8 ignore next -- sort_order is NOT NULL DEFAULT 0; the ?? fallback is unreachable */
     sort_order: row.sortOrder ?? 0,
   };
 }